Many machinery applications require lubrication to a bearing or bearing surface that is positioned on a spindle. One way to achieve this objective is to provide a lubricant passageway that is coincident with the spindle axis. By means of a grease zert or other grease receiving element that can be threaded or pressed into the end of the spindle, grease can be injected through the lubricant passageway, the lubricant traveling through the passageway until it encounters a second lubricant passageway which communicates, at one end, with the first lubricant passageway and, at that other end, with a lubricated area on the spindle. This system works well except it introduces a problem, that is, the problem of keying a nut threaded onto the spindle at the outer end. That is, it is very common to employ a pin or cotter key to extend through the spindle in the threaded area so that a nut positioned on the spindle can be held in position. The problem then arises as to the interference between the first lubricant passageway and the key opening. Since these openings intersect, grease injected into the passageway can pass out of the key opening. In addition, a key, when inserted in the key opening, interferes with the passage of grease along the first lubricant passageway.
One way to overcome this problem is illustrated in U.S. Pat. No. 5,120,170 entitled "Apparatus For Retaining A Nut On A Spindle". In this patent the first lubricant passageway is coaxial with the spindle axis. However, to avoid the intersection of the key opening with the lubricant passageway, the key opening is offset from the center of the spindle. That is, the key opening is drilled along a chord midway between the lubricant passageway and the peripheral exterior of the spindle threaded portion. A pin, such as a cotter key, can then be inserted in the key opening to pass through openings or slots in a nut to lock the nut onto the spindle.
A problem with the system of U.S. Pat. No. 5,120,170 is that the placement of the key opening on a chord of the spindle makes it difficult to align a pin with openings or slots in a nut. In U.S. Pat. No. 5,120,170 the nut illustrated is termed a "castellated nut", that is, a nut that has several circumferentially spaced slots. A cotter pin extending through a key opening that is a chord of the spindle end requires wide slots in the nut.
Further, it is difficult to drill a cordial hole through a spindle. A special fixture is usually required to prevent the hole being drilled from wondering and to prevent drill bit breakage.
The present invention intends to address the problems encountered with U.S. Pat. No. 5,120,170 by providing a spindle having a lubrication passageway that communicates with the end of the spindle and also has a key opening, but wherein the key opening is in the center of the spindle, that is, it passes through the axis of the spindle to engage slots or holes in a nut so that the slots or holes are not required to be any larger in width or diameter than the diameter of the key opening or the diameter of the key being used to retain the nut.